The invention relates to a device for determining material moisture by thermogravimetry, comprising a test chamber that is delimited by a chamber cover, a microwave field which can be generated by a magnetron and fed via a waveguide to a test chamber, a tuning rod arranged in the test chamber, a sample carrier which is in operative connection with a weighing module mounted upstream of the test chamber, and at least one sensor arranged in the test chamber.
The invention also relates to a method for determining material moisture wherein a sample placed on a sample carrier in a test chamber has moisture removed therefrom by heating in a microwave field generated by a magnetron and fed to the test chamber via a waveguide, while being monitored by at least one sensor and the weight of the sample is determined by a weighing module before and after moisture removal and used in a computer unit to determine the material moisture.
Devices and methods for thermogravimetric material moisture determination are used in industrial laboratories, mainly in the food and drink industries and the chemical and pharmaceutical industries, but also in the cosmetics, animal feed and building material industries for thermogravimetric material moisture determination.
U.S. Pat. No. 6,247,246 B1 discloses a device for thermogravimetric material moisture determination, which comprises a cylindrical test chamber with a sample carrier in operative connection with a weighing module, onto which sample carrier the sample to be measured is placed. A microwave field generated by a magnetron can be fed to the test chamber via a waveguide to desiccate the sample. The moisture removed from the sample can be drawn off by fans via apertures in the chamber cover which end in at least one exhaust air channel. The known device has at least one microwave sensor in the chamber cover. In addition, a gas or smoke sensor and a sensor for detecting light or light flashes can be arranged in the chamber cover. In order to allow the microwave field to act effectively on the sample, two tuning rods are arranged laterally of the sample at the test chamber base, adjacent to two portals for feeding the microwaves into the test chamber.